It is a technical challenge to provide a small-sized ion source excellent in operability.An ion source of the present invention includes: a cylindrical insulation tube (2) opened upward and opened at part of its lower surface; a plurality of hollow cylindrical permanent magnets (3), provided on the outer peripheral surface of the insulation tube to be arranged in a row in the axial direction of the insulation tube; a gas supplying means (34, 35, 20) for supplying gas into the insulation tube; a cathode electrode, at the tip end of which a fitting unit (19) for fitting of a solid material (18) there to is formed; an annular anode electrode (5), which is fitted to an opening in the lower surface of the insulation tube; an upper frame (6), which blocks the upper portion of the insulation tube and suspends the cathode electrode so as to allow the fitting unit to approach the anode electrode; and a lower frame (7), in which an extraction port (37) is formed for extracting ions emitted from the anode electrode, and on which the insulation tube is mounted.